1. Technical Field
The present invention relates generally to a battery terminal and a method for making the same.
2. Description of the Related Art
It is known generally to provide an electric storage battery of the type having external terminals on the side or end walls of the battery case. Typically, such terminals are not of the post type, but rather are of the recessed, threaded female type terminal, as seen by reference to U.S. Pat. No. 5,814,421 to Spiegelberg et al. Spiegelberg et al. disclose a method for forming such a battery terminal having a threaded hard metal insert received within an outer portion formed of lead, the lead portion being deformed (i.e., cold worked) by an orbital head-forming apparatus to secure the hard metal insert within the outer lead portion. Spiegelberg et al. further disclose that the outer portion includes a spline ring to prevent rotation of the terminal within the battery housing. Spiegelberg et al. also disclose sealing rings on the outer lead portion and which are molded into the case. The anti-rotation approach in Spiegelberg et al., however, does not provide satisfactory resistance to rotation in certain circumstances and the sealing approach requires a complicated insert molding process or the like.
It is further known to insert a partially formed battery terminal from the outside of the battery case, and secure and finish the terminal through cold working of the terminal through an orbital finishing step performed on an inwardly facing portion of the terminal (i.e., towards the interior of the battery case). However, it has been found that the cold worked lead, which is exposed to acid (e.g., sulfuric acid solution in a lead-acid battery), results in accelerated corrosion, which may result in acid solution leaking out of the battery case in and around the terminal area.
There is therefore a need for an improved battery terminal that minimizes or eliminates one or more of the problems as set forth above.
One advantage of the present invention is that it provides an exterior (i.e., on the outside of the battery case) spin riveted terminal to eliminate the interior (i.e., interior of the battery case) lead cold working to thereby minimize corrosion as described in the Background, and the accompanying leakage associated therewith. Another advantage of the present invention is that it provides an anti-rotation arrangement of interlocking bosses/slots that provide a torque-turning resistance that is improved over conventional approaches taken in the art. Another advantage of the present invention is that it provides a battery terminal having a sealing system configured to seal the battery terminal area to thereby prevent or minimize leakage of fluid, such as sulfuric acid solution. Still another advantage according to the present invention is that it provides a battery terminal having a mechanism for minimizing or eliminating acid stratification, which minimizes corrosion (as described in greater detail hereinafter).
A battery terminal according to the invention is configured to be secured to a battery case from an exterior side thereof. The battery terminal comprises a terminal assembly, a ring, and a terminal anti-rotation system. The terminal assembly extends generally along a main axis and includes (i) an insert having a threaded bore and (ii) an outer metal portion having a base with an annular flange configured to engage an inner surface of the case. The terminal assembly is inserted from the inside of the case. The ring is configured to be disposed over the terminal assembly from the exterior of the case. The anti-rotation system includes a first set of angularly-spaced bosses with intervening slots formed on a case boss on an outer surface of the battery case. The anti-rotation system further includes a second set of angularly-spaced bosses with intervening slots on a first side of the ring that faces the case boss when inserted over the terminal assembly. The second set of bosses/slots are complementary with the first set to form a first pair of interlocking features. The anti-rotation system also includes a set of recesses on a second side of the ring opposite the first side configured to receive portions of the terminal assembly that are subsequently deformed into such recesses.
In a preferred embodiment, the portions of the terminal assembly to be received into the set of recesses comprise the distal end portions of the terminal assembly which are, at least in part, deformed in accordance with an orbital spin coldworking operation. A second preferred embodiment is also presented wherein the terminal assembly and the ring are joined using a welding operation.
In a still further embodiment, the battery terminal further includes (i) an inventive sealing system and (ii) radial bores that allow acid solution to communicate between the main interior of the case and an interior seal which is located in an annular groove.